E85 Ethanol Fuel Test - The E85 Solution
We test a 105-octane fuel that costs less than 87 pump gas and makes the same power as race gas
This is what happens when you use a standard-heat-range spark plug in a high-compression m
Engine Anatomy
Since everybody knows that small-block Chevys grow on trees in Southern California, we stopped outside Ed Taylor's Ventura shop one afternoon and picked a ripe 12.5:1 compression 355ci short-block for our test. Fitted with a strong Scat steel forging crank and I-beam rods rotating assembly with a set of SRP forged pistons, we opted for more compression to really put E85's octane rating to the test. Next we bolted on a set of Dart Platinum iron 215cc heads fitted with 2.05/1.60-inch valves. These are the latest wet-flow-technology heads available from Dart, and our flow data reveal the 215s to be a good choice for this test.
Since we wanted to push this small-block a little harder, we opted for a complete mechanical roller cam setup from Crane that pushes the valves open to 0.561 inch lift with 250/258 degrees of duration at 0.050 inch tappet lift. Combined with Crane's recommended valvesprings and set of titanium retainers, we also added a set of Crane Gold Race 1.6:1 rockers to ensure the valvetrain easily spins to 7,000. Moroso supplied the oil pan and pump that we filled with lightweight Royal Purple 5W-20. Since this was an rpm application, we went with an Edelbrock Super Victor single-plane topped with a Quick Fuel Technology 850-cfm annular discharge carburetor and an MSD billet distributor and 6AL ignition box. For the exhaust, we used a set of Hedman 1 7/8-inch headers hooked to a pair of 2 1/2-inch Flowmaster mufflers.
While the engine ultimately made 466 hp, our goal had little to do with ultimate power. (As it is, this engine made 1.3 hp/ci.) Of much more concern for this test was an engine that was both durable and repeatable and would allow us to evaluate the differences in fuel between race gas and E85. From that standpoint, this little 355 was a success.
One of the first things we learned is to invert the float bowl to level the float and then
Metering-Block Mania
At first, we thought all we had to do was plug bigger jets in a standard metering block to compensate for the less Btu output of our E85 fuel and we'd be in business. But after our test and in talking with the guys at Quick Fuel, there's more to this business than a quick jet change. They told us our test with the standard Quick Fuel metering blocks indicated it might be better to start with methanol-style metering blocks and then add the internal air bleeds that will help establish the proper fuel curve. This is because a standard Holley metering block maxes out in terms of fuel delivery with jets around 92 and a 0.070-inch power-valve channel restriction (PVCR). Increasing the jet size or PVCR beyond these points delivers a smaller percentage of fuel-flow increase. This is why drilling out the PVCR on our billet blocks didn't help all that much. It should have drowned the engine in fuel, but it was actually only worth a small percentage of additional fuel. The part number listed in the parts list is basically a methanol metering block configured with bleeds tuned for E85. This will guarantee sufficient fuel-flow capability to feed any normally aspirated engine.
The Dyno Test
Our test concept was simple-run the engine on race gas, establish a repeatable power baseline and then modify the carb with new metering blocks, change fuel to E85, and see what happens. After we repaired the damage from our experiment with heat-ravaged spark plugs, the motor responded with a pleasant and repeatable 460 hp on a 50/50 mix of 117-octane race gas and 91-octane pump gas. In theory, this produced an AKI of 104. After a few jetting and timing experiments, we came up with a peak horsepower number of 466 at 6,800 rpm. Now we were ready to test the E85.
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